(1) Field of the Invention
This invention is concerned with apparatus for feeding adhesive in rod form progressively to a melt chamber, said apparatus comprising a first tubular portion through which a rod of adhesive can pass and be guided thereby and which can be connected to a melt chamber, and a device by which the rod of adhesive can be engaged and which is movable, between a retracted and an advanced position, relative to the first tubular portion, whereby to feed the portion of adhesive rod accommodated in the latter to the melt chamber.
(2) Prior Art
Apparatus is described in U.K. Patent Specification No. 1301275, in which apparatus the first tubular portion is provided with opposed slots, in which opposed jaws of the rod-engaging device can project to grip on a rod of adhesive accommodated in the tubular portion. Apart from the expense of machining the slots in the tubular portion, however, the provision of such slots from time to time proves detrimental in that they so weaken the tubular portion that, in the event of an obstruction arising therein, with consequent buckling of the rod of adhesive, the tubular portion itself may be distorted.
In another proposed apparatus for feeding adhesive in rod form (see e.g. U.S. Pat. No. 3,743,142), the adhesive rod is gripped at its position spaced from the tubular portion and, as the rod-engaging device is advanced towards the first tubular portion, the adhesive is fed therethrough. The adhesive rod is unsupported, however, in such an arrangement between the gripper and the "upstream" end of the first tubular portion, and in some instances the possibility therefore arises of a blockage taking place in the first tubular portion with a result that the unsupported portion of the rod becomes buckled. In such an instance, the buckled rod can then no longer be fed, and the unit has to be cleared of adhesive before its use can be continued.
It is the object of the present invention to provide an improved apparatus for feeding adhesive in rod form, in the operation of which the risk of buckling of the rod is minimized, control of the rod being however, achieved using relatively inexpensive components.